The present invention relates a data processing system, data management method and storage system for providing a dynamically capacity-expansible storage region to a host computer.
In recent years, a storage system for providing a storage region of data to a host computer is able to have a multitude of large capacity physical disks, and massive enlargement of the storage capacity is making progress. With this kind of storage system, foremost, a disk array configured in RAID (Redundant Array of Independent Disks) is created from physical disks, and a plurality of such physical storage resources are gathered to create a pool area, and a storage region of the capacity requested by the host computer from the pool area is created as a logical volume and provided to the host computer.
Here, pursuant to the massive enlargement of the storage system, the size of the storage region requested by the host computer is also becoming enlarged, and a large quantity of physical disks to cover the entire capacity must be prepared at one time upon introducing the storage system. Nevertheless, as a result of technological changes, a more reliable storage system can be created by adding physical disks that are newly introduced. Further, certain clients are not able to determine the capacity to be prepared, and there are cases where it is not possible to decide the quantity of physical disks to be prepared.
Thus, technology has been invented for adding physical disks as necessary when the disk capacity utilization nears maximum capacity without preparing physical disks from the initial stages of introduction for the entire capacity to be provided to the host computer, and dynamically changing the storage capacity to be provided to the host computer (e.g., refer to gazette of Japanese Patent Laid-Open Publication No. 2003-015915, hereinafter “Patent Document 1”).
With this technology, in the foregoing storage system, a logical volume of a fixed capacity is not created from the pool area, and a virtual logical volume is foremost provided to the host computer. And, the dynamic capacity expansion is realized by dynamically assigning a storage region, which is a certain unit (the unit of this storage region is hereinafter referred to as a “segment”), to the virtual logical volume according to the I/O (Input/Output) from the host computer.
Further, when the operation employing the storage system is continued, data of low frequency of use will remain stored in an expensive disk that is highly reliable, responsive and endurable. Here, there is a problem in that an overly expensive disk capacity will be used, and an expensive disk cannot be efficiently used.
Nevertheless, under US laws and regulations, email data and medical data must be stored for a fixed period of time even if the frequency of use thereof is low. Thus, technology has been invented for migrating data from an expensive disk to an inexpensive disk which is inferior in terms of reliability, responsiveness and endurance in comparison to such expensive disk (e.g., refer to gazette of Japanese Patent Laid-Open Publication No. 2000-293317, hereinafter “Patent Document 2”; specification of U.S. Pat. No. 6,108,748, hereinafter “Patent Document 3”; and gazette of Japanese Patent Laid-Open Publication No. 2003-345622, hereinafter “Patent Document 4”).
As the data destination, there are a storage region in the same storage system (refer to Patent Document 2), a storage region of different storage systems (refer to Patent Document 3), and a storage region of different storage systems being managed virtually as a single storage system (refer to Patent Document 4). Further, this technology is also used for dividing data into a plurality of disk arrays to perform load balancing when I/O from the host computer is concentrated on a single disk array configuring RAID.